High speed train control equipment



ct. l1, 1938. C, MCCUNE I HIGH SPEED TRAIN CONTROL EQUIPMENT Fired Nov.` 19, 1956 5 Sheets-Sheet 1 INVENTOR JOSEPH C. MCCUNE, BY

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INVENTOR JOSEPH C. MCCUNE.

ATTORNEY Smm.,

Patented Oct. 11, 1938 UNITED` STATES PATENT OFFICE HIGH SPEED TRAIN CONTROL EQUIPMENT Application November 19, 1936, Serial No. 111,690

49 Claims.

This invention relates to high speed train brake control equipment and particularly to brake control equipment adapted to prevent sliding of the car wheels.

The problems incident to the adequate and safe braking of railroad trains which travel normally at heretofore unprecedented high speeds, for example in excess of one hundred miles per hour, are many and various. One of the most salient and important of these problems is the problem of preventing sliding of the car wheels, that is, a condition wherein the wheels are held frictionally against rotation, due to the application of the brake shoes to the car wheels with such excessive braking force as to overcome the adhesion between the wheels and the track rails while the train continues to travel along the rails,

Adhesion between a wheel and the rail along which it rolls is usually expressed as a coeiflcient of adhesion, which is the ratio between the maximum tangential retarding force that can be effective on a wheel without causing it to slide, and the Weight or load pressing the wheel to the rail. The coeicient is usually expressed as per cent oi.' the weight pressing the wheel to the rail.

Heretofore known high speed train brake control equipments which were designed to so control the application of the brakes as to prevent sliding of the car wheels are of two general types which may be designated as, (l) the speed-governor type and 2) the inertia-governor type.

The speed-governor type of retardation control equipment comprises essentially a governor device which is driven according to the speed of the train and which operates automatically, as the speed of the train reduces, to reduce the braking force on all the cars of the train in one or more steps so that, at the lower speeds, the braking force will be insufiicient to cause sliding of the car wheels.

The inertia-governor type of control equipment comprises an inertia element which may be in the form of a pendulum, a mass on rollers, or a iiywheel, which is actuated according to the rate of retardation of the train to reduce the braking force on all the cars of the train, as the speed of the train decreases, so that a substantially constant rate of retardation is maintained.

In the speed-governer type of brake control equipment, the braking force is controlled solely according to the speed of the train and accordingly no change in braking force occurs as long as the speed of the train remains constant. In the inertia-governor type of brake control equipment, the reduction in braking force with the reduction in train speed is not as arbitrary as in the speed-governor type, in view of the fact that the response of the inertia-governor is affected by the increase in the coeflicient of friction between the brake shoes and the car wheels resulting from the reduction in the speed of the train and also from the reduction in the braking force applying the brake shoes to the car wheels.

Both types of equipment are designed to limit the maximum braking force to a degree which will not cause sliding of the wheels under what will hereinafter be termed poor rail conditions, that is, conditions under which the coefficient of adhesion between the car wheels and the track raih is a relatively low value, such as fifteen per cent. The maximum braking forces thus effective in the case of either type of equipment is, in most instances, actually less than rm'ght be applied without causing sliding of the wheels, since the usual condition is what will hereinafter be termed a good rail condition, that is, a condition under which there is a relatively high coeiiicient of adhesion between the car wheels and the track rails, such as twenty-ve per cent,

It Will be apparent, therefore, that in either the speed-governor type or inertia-governor type of brake control equipment, the maximum value of braking force is restricted to a value which is lower than might be applied without causing sliding of the wheels, in order to provide a factor of safety to guard against excessive sliding of the wheels at certain times. It follows, therefore, that the length of the stop, that is, the distance which the train travels from the time the application of the brakes is initiated until it is brought to a complete stop, is greater compared with what it would be if higher braking forces were applied.

In contrast to the principle of design and operation of th-e speed-governor and inertia-govrncr type of brake control equipment, namely,

that the usual condition is a poor rail condition and that the good rail condition is the exception, the brake control equipments which I have devised are designed to operate on the assumption that the usual condition is a good rail condition and that the occurrence of a poor rail condition is the exception.

In arriving at this basic principle of my invention, I have been guided by the results of reliable tests carried on under various weather conditions over a period of months, which tests indicate that a relatively high coeflicient of adhesion, such as twenty-live percent, may ordinarlly be dependably realized at least seventyiive per cent of the time the train is in service.

The o-utstanding advantage of a brake control equipment designed in accordance with the basic principle stated above is that higher braking forces or braln'ng ratios are permitted and thus a train may be stopped in a much shorter distance from a given high speed, Without sliding o-I" the wheels, as compared with the stopping distance capable of being effected by any of the types of brake control equipment for high speed trains heretofore proposed or known.

The penalty paid, in terms of stopping distance, by a brake control equipment designed to function on the basis of a single relatively low coefficient of adhesion between the wheels and the track rails has been appreciated to a certain extent by those working in the art and an improved type of inertia-governor device has been proposed which may be adjusted manually by the engineer or the driver of the train to increase or decrease the rate of retardation of the train, as regulated by the governor, accordingly as in vthe judgment of the operator, such adjustment may be safely mada However, in any case the operator or engineer will play safeand allow a certain margin oi safety so that the inertia-governor will not permit a braking force to be effected which is apt to cause sliding of the wheels. Thus, due to this margin of safety, the benefit of an actually higher coefficient of adhesion is not fully taken advantage of, as reflected in the higher braking forces or braking ratios which might be eiected without causing sliding of the wheels.

An additional characteristic of the inertia-governor type of brake control equipment for high speed trains is that the inertia-governor device is responsive to the rate of retardation of the train as a whole and does not register the individual rates of retardation of individual Wheels or individual wheel-and-axle units` Sliding lof an individual wheel or wheel-and-axle unit is accordingly not reiiected in the operation of the inertia governor device in such Vmanner as to cause a release of the brakes associated with the particular wheel or wheel-and-axle unit which is beginning to slip or whi-ch is actually sliding. As a matter cf fact, the braking effect exerted by a car wheel which is sliding is less than that exerted by a car wheel which continues to roll and which has a maximum retarding force exerted thereon, as determined by the coefficient of adhesion between the wheel and the rail. It might thus happen that if a sufficient number of wheels orV wheeland-axle units begin to slide, the inertia-governor device will interpret the sliding wheel condition as a diminution in theY braking effect and operate to increase` the braking force, which is directly opposite to the eifect which is desired, namely, a decrease in braking force.

i In order to guard against sliding of the wheels by controlling the braking force applied to individual wheels or wheel-and-axle units, it has been proposed to provide an anti-wheel-sliding device which comprises an inertia body in the form of a ily-wheel which is.normally driven according to the speed of the train'and which shifts yieldingly relative to a driving element when an individual wheel or wheel-and-axle unit begins to slip, that is decrease from a speed corresponding to the speed of travel of the train to zero speed corresponding to a' locked position. Such an anti-wheel-sliding device is disclosed and claimed in the copending application Serial No. 713,103 of Rankin J. Bush, filed February 27, 1934, now Patent 2,068,370, and assigned to the assignee of the present application. In the device disclosed in the copending Bush application,

braking force, or braking ratio, as exemplified byy brake cylinder pressure, is rapidly reduced at the time a wheel or wheel-and-axle unit begins to slip, so that before the Wheel or wheel-and-axle unit actually reaches a locked condition, the brake cylinder pressure has been reduced to such an extent that the wheel or wheel-and-axle unit begins to accelerate back toward its normal speed, corresponding to the speed of travel of the train, whereupon the original braking force is restored.

One limitation ofsuch an anti-wheel-sliding device is that, should the wheel or wheel-andaxle unit again begin to slip, upon the reapplication of the braking force, the braking force or brake cylinder pressure is again reduced, thereby wasting a considerable quantity of Yiiuid pressure medium or air. On a single car or on a train consisting of two or thre"`"cars, such consumption of air might be tolerable, but on a relatively long train of fifteen or twenty cars, the total consumption of air from the fluid pressure systemvvould be intolerable for the reason that the fluid pressure in the system might be dissipated or reduced to such an extent as to render the other remaining fluid pressure brakes inadequately eirective.

In my present invention, I propose to employ a device which locally controls the braking force orbrake cylinder pressure of individual wheels or wheei-and-axle units to immediately and rapidly reduce the braking force or brake cylinder pressure in the event that the wheel or wheeland-axle unit begins to slip, but which, in contrast to the device of the copending application above mentioned, functions to permit the restoration of a braking force or brake cylinder pressure which is less than that which initiated the wheel slipping condition. AsV a result, a repetition of the wheel slipping condition is unlikely upon the reapplication of the braking force since the braking force has been diminished. Consequently, air is not repeatedly vented from the brake cylinder and thus undue and unnecessary waste of air and the reduction of the pressure in the fluid pressure system, even for long trains, is obviated.

. In my prior copending application, Serial No.

718,376, filed March 31, 1934, there is disclosed and broadly claimed an equipment for releasing the brakes and controlling the degree of 1'eappli cation of the brakes on a vehicle wheel upon slipping of the wheel due to excessive application of the brakes; and the claims inV this application covering this feature of my present invention are accordingly directed to the specific structure disclosed herein.

It is accordinglyan object of my invention to provide brake control equipment for high speed trains which will enable shorter stopping distances, without causing sliding of the vehicle wheels, than have been obtainable by brake control equipment heretofore proposed.

Another object of my invention is the provision of a device which functions both in the capacity of a retardation controller for so regulating the brakingv force under ordinary conditions as to cause the train to be brought to a stop at a substantially constant and heretofore unattained maximum rate of retardation, and which functions when a Wheel or wheel-and-axle unit begins to slip to inhibit or prevent sliding of the wheels.

Another object of my invention is to provide apparatus, including a device of the character described in the foregoing object, adapted to reduce brake cylinder pressure to prevent sliding of the wheels, with minimum wastage of fiuid under pressure.

Another object of my invention is to provide an arrangement including the apparatus mentioned in the two foregoing objects which is adapted to function automatically for either a forward or backward direction of travel of a car or train.

Another object of my invention is the provision of a brake control equipment for high speed trains of the character indicated in the foregoing objects, in which the conversion of present-day standard equipment to the type of equipment which I propose may be accomplished in a relatively simple and inexpensive manner by employing the usual signal pipe of present-day equipment.

The above objects and other objects of my invention which will be made apparent hereinafter, are attained by means of several illustrative em` bodiments of my invention subsequentlyy to be described and showrr in the accompanying drawings wherein,

Fig. l is a diagrammatic view, showing one embodiment of my invention in a double-end equipment adapted for travel of the car or train in a forward or backward direction, certain of the `parts being shown in outline or in simplified form,

Fig. 2 is a view, partly in section and partly in elevation with portions broken away showing in detail, the construction and method of mounting the adhesion adapter, indicated in simplified form in Fig. l,

Fig. 3 is a sectional view,` taken on the line 3- of Fig. 2. showing in further detail the construction of the adhesion adapter,

Fig. 4 is a diagrammatic View, showing the electrical connections between the collector rings at one end of the hub of the adhesion adapter device With the contact segments at the opposite end thereof,

Fig. 5 is a diagrammatic sectional View, showing the essentials of the control valve mechanism, indicated in outline form in Fig. l,

Fig. 6 is a diagrammatic view, showing a brake control system, which differs from that shown in Fig. 1 in that it is a single-end equipment rather than a double-end equipment, that is, it is adapted to operate for travel of the car or train in a forward direction only, and

Fig. 7 is a diagrammatic View, vshowing a modified form of the brake control system shown in Fig. 6 and differing therefrom in that control of the equipment on successive cars of the train is effected through the medium of the familiar signal pipe present in the brake equipment of present-day railroad trains.

DESCRIPTION or EQUIPMENT Referring to Fig. l of the drawings, the embodiment shown comprises any conventional fluid ressure brake system, such as a straight-air system represented by a main reservoir iI, brake cylinder I2, a pipe I3 hereinafter called the straight-air pipe and through which iiuid under pressure is supplied to the brake cylinder I2, and a manually operable self-lapping brake vaive device I4, of well known construction, such as shown in the Patent 2,042,112 of Ewing K. Lynn and Rankin J. Bush, foiI controlling the supply of fluid under pressure from the main reservoir lI to the straight-air pipe I3 and brake cylinder I2 to cause application of the brakes and the release of fluid under pressure from the straight-air pipe I3 and brake cylinder I2 to release the brakes. It is deemed unnecessary for present purposes to describe the construction and operation of the self-lapping brake valve I4 in detail, it being necessary only to understand that the pressure established in the straight-air pipe I3 is in accordance with the degree of movement of the operating handle I5 of the brake valve device ifi from a normal release position into an application zone.

According to my invention, the equipment shown in Fig. l also includes a control valve mechanism I6 which is interposed between the straight-air pipe I3 and the brake cylinder I2 to control the supply of fluid under pressure from the straight-air pipe I3 to the brake cylinder I2 and the release of fluid under pressure from the brake cylinder in a manner subsequently to be described. A so-called adhesion adapter I8, indicated in simplified form in Fig. l and shown in detail in Figs. 2, 3 and 4, and a similar adhesion adapter IBa are provided for controlling the operation of the control valve mechanism i5, the adapter devices I8 and I8a being associated respectively with the front and rear axles of a Wheel-truck. A pair of direction-determining relays iS and I9a, for rendering the adhesion adapter devices suitable for either forward or backward travel of the car or train, a suitable Source of electric current, such as a battery (22, a pair of train wires 24 and 25, a pneumatic interlock switch 21, a retardation control relay 3I, and a Wheel-slip control relay 29 are also provided.

It will be understood that the equipment shown in Fig. 1 is adapted te control only the brakes for the particular wheel-truck with which the adhesion adapter devices I8 and ISa are associated. It will be understood that for simpiicity, .f

only one brake cylinder is shown together with associated control equipment including the control valve mcchanism IB, the adhesion adapter devices I8 and IBa, and the relays I9, I9a, 29 and 3I. Repetition of brake cylinders for successive wheel-trucks throughout the length of the train, together with repetition of control valve mechanism i6, adhesion adapters Hl and IBa, and relays I9, I9a, 29 and 3| for each control valve mechanism is according-uy deemed unnecessary. It will, furthermore, be understood that the brake control equipment comprising my .invention may be embodied in any type of fluid pressure brake system and Whether the cars of the train are of the articulated or the non-articulated or usual type.

(a) Adhesion adapters 18 and 18a The adhesion adapter devices I8 and I8a. are identical in construction and, accordingly, only the adapter device I3 will be described. The parts of the adhesion adapter device I8a will be understood to have the same reference numerals as for the device I 8 except that the suffix a will be added. The adhesion adapter device I8 comprises a casing or housing (Fig. 2) which is suitably mounted on and attached to a portion of the wheel-truck frame 33. the housing be ing split and having a lower portion which is removably secured to the remainder of the housing` The separable portions of the housing 32 are provided with semi-circular recesses adapted to register when the portions are secured together to form openings 35 in each side of the housing through which an axle 36 of the wheel-truck extends. In the case of the adapter device I8, the axle 35 is the front or leading axle of the truck. In the case of the adapter device la, the axle is the rear or following axle of the same wheeltruck. The openings 35 in the housing 32 are sufficiently larger in diameter than the diameter of the axlei that the usual movement of the axle relative to the wheel-truck is not interfered with. Suitable split packing rings 58 are provided for each of the openings 35, the rings SS having annular flanges substantially perpendicular to the axis of the axle which engage in circular grooves 39 formed in the housing at the openings 35, the groove 35 being sufficiently large in diameter to permit the up and down movement of th-e axle with respect to the housing without interfering with the sealing function of the packing ring.

Contained within the housing 52 is a wheel lili, having a hub 53 which is provided at each end with suitable bearings, such as the ball bearings fi, for rota-tively mounting the hub and wheel it on a shaft or rod which is, in turn, carriedV on a yoke l5 suitably mounted within the housing. The yoke i5 has two prongs there being suitable openings i8 at the end of the prongs thro-ugh which the shaft l5 extends. Suitable pins le extend transversely through the shaft i5 at each end so as to secure the shaft 55 against movement relative to the yoke fifi; l

The shaft i5 is of such length that the ends thereof project beyond the prongs il and engage in suitable vertical slots or openings 5l in the opposite side walls of the housing 32.

The slots 5i conform closely in width tothe diameter of the shaft i5 so as to prevent lateral movement of the yoke #l5 in the housing while at the same time permitting movement of the yoke relative to the housing 32 in opposite directions longitudinally of the slots 5l.

Suitable cover plates 52 may be providedto cover the openings 5l to prevent the entrance of dust or dirt particles into the interior of the h-ousing 32.

Detachably secured to hub 53, as by a key 59, is a driving wheel il having a rim 42 of friction material attached thereto. The yoke i5 is yieldingly urged toward the axle 35 by a relatively heavily tensioned coil spring 53, which is interposed between the top wall of the housing and the central or base portion of the yoke 36, the rim i2 of the wheel di being accordingly yieldingly urged into frictional contact with the outer surface o-f the axle 36 so as to maintain the axle and the wheel il in driving engagement. The wheel lil, the hub 53, and the wheel are thus driven or rotated in accordance with rotation of the axle 35, that is, at a speed corresponding to the speed of rotation of the car wheels. It will be understood that the wheel il may be driven by rotation of the axle 35 in'any other suitable manner, as by gear or pulley and belt arrangements.

The spring 53 encircles and is, in part, held in position by a projecting stem 5d, secured or attached to the central portion of the yoke, which stem 513 extends through an opening 55 in the top wall of the housing and is slidable therein whereby to guideV and suport the upper or base end of the yoke. A removable collar 56 may be secured to the end of the stem 5ft for engaging the top surface of the housing 32 and thereby limiting the extent of the movement of the yoke and the wheel toward the axle 36 under the influence of the spring 53. The openings 5l, however, may be so positioned and of such length as to perform this function without the aid of the collar 56, the engagement of thershaft 45 with the side Walls of the housing 32 at the end of the openings 5i toward the axle, serving the same purpose.

The driving wheel 4l has an annular recess 5l, in one face thereof, surrounding the hub 53. Positioned within the recess 57 is an inertia body, in the form of a flywheel 58, which is suitably mounted forY rotative mo-vement relative to the hub 43 and Wheel G5, as by ball bearings 59 interposed between the outer surface of the hub 53 and the central opening in the hub portion of the fly-wheel.

Af resilient yielding connection between the fly-wheel 58 and the hub i3 is provided, according to my invention, by means df a suitable coil spring 65 contained in a transverse bore 5l extending through the hub 513 to one side of the shaft 5. The spring 5! is interposed between a pair of discs 52 and 53 for urging them in opposite directions outwardly of the bore 5l, the discs being held in the bore by means of set screws 64 screwed into the opposite ends of the bore. Each of the discs 52 and 53 is provide-d with a stem VE55 attached to or formed integral therewith, which extends through a suitable central opening in the corresponding set screw 6G and projects out of the bo-re 5| beyond the periphery of the hub 53.

A pair of adjustable stop screws 55 and 5l are attached to the hub portion of the fly-wheel 53 asby angle brackets 68 in such manner that the stop screw 55 is in coaxial relation to lthe stem of disc 52, with the inner end of the stop screw engaging the outer end of the stem of the disc 62, while the stop screw 5l is in coaxial relation to the stem of the disc 83 with the inner end of the stop screw engaging the outer end of the stem of the disc 63.

The stop screws 55 and 5l are screwed into suitable threaded openings in the angle brackets 68 and may be adjusted inwardly or outwardly, as by a screw driver engaging the outer end thereof, to vary the tension of the coil spring G. screws 65 and 6l with comparative ease, the outer rim of the wheel is pro-vided with suitable openings 69 therein in line with the stop screws 65 and 6l to enable the shank of a screw driver toV extend therethrough to the outer end of the stop screws. Suitable lock nuts i5 are provided for locking the set screws and 5l in position after they are adjusted to the proper position.

The tension in the spring 6B may also be varied by turning the set screws 54 inwardly or outwardly of the bore 6|. The stop screws F55 and 5l are then adjusted into contact with the rounded ends of the stems of the discs 62 and 53, respectively, so as to prevent any lost motion or play between the iiy-wheel and the hub 53.

It will thus be apparent that upon acceleration of the driving wheel i and' hub 53 relative to the fly-wheel 58, the coil spring 65 yieldingly resists inward movement of one or the other of the discs 52 or 53, the degree of rotative movement of the fly-wheel relative to the hubbeing dependent upon the tension of the spring 55 and upon the rate of acceleration of the driving wheel 4I. On the other hand, if the driving wheel il is retarded, the fly-wheel 53 tends to rotate relative thereto in the opposite direction, against the force of the spring 60, to a degree dependent upon the rate of retardation of the wheelli i When the driving Wheel 4I is rotating at a substantially constant rate of speed without any change in the In order to enable adjustment of the stopV speed thereof, the fly-wheel 58 assumes a normal or neutral position with respect to the hub, as shown in Figs. 2 and 3.

By providing a single spring B0, instead of a plurality of different springs, a uniform degree of shifting of the fly-wheel 58 in either direction relative to the hub 43, for the same rate of retardation or acceleration is secured.

Suitably secured to and encircling the outer surface of one end of the hub 43 is a ring 8| of insulating material having a pluralityl` of peripheral grooves spaced longitudinally of the hub in which are received a plurality of collector rings 82, 83, 84, 65, 86, 81 and 88.

Suitably mounted on one prong 41 of the yoke 46, as by a bracket 9| attached to the prong, are a plurality of brushes, 92, 93, 94, 95, 96, 91 and 98 arranged in a row for contacting the collector rings 82 to 88, respectively, the usual brush holders and biasing springs for the brushes being omitted for simplication. Suitable flexible wires, |02, |03, |04, |05, |06, |01 and |08 are connected to the brushes 92 to 98, respectively. The wires |02 to |08 extend from the brushes 92 to 98 through an opening |00 in one prong 41 of the yoke 46, in which opening is a bushing III of insulating material, and thence to the exterior of the housing 32 through an opening IIO in the housing having an annular bushing |I2 of insulating material secured therein. Suitable calking or sealing material may be provided to support the Wires in the bushings III and I|2 as well as to Vprevent the entrance of dust or dirt into the interior of the housing 32. The individual wires |02 to |08 are provided with suitable insulation to guard against short-circuiting of the brushes 92 to 98.

Suitably secured in a recess 12 in the outer surface of the rim of the wheel 40 is an arcuate segment II3 of insulating material having spaced parallel grooves therein, in which are removably and adjustably secured (see Fig. 4) a plurality of switch members in the form of arcuate contact segments |I5, IIS, |I1, II8, II9, |20 and I2|. The contact segments IIB, II8 and |20 are disposed on one side and the segments II1, II9 and I2I on the opposite side of a neutral plane which extends through the mid-point of the segment |I5 in perpendicular relation to the longitudinal axis of the segment II5. The contact segment IIS is in alignment with the segment II1, the segment I8 is in alignment with the segment I I9, and the segment |20 is in alignment with the segment I2I.

The inner ends of the segments II6 and |I1 are equidistant from the neutral plane, as are the inner ends of the segments II8 and II9, and the inner ends of the segments |20 and I2I. The distance from the neutral plane to the inner end of segments II6, IIB and |20, respectively, is successively greater, and the distance from the neutral plane to the inner end of the segments |I1, I|9 and I2I, respectively, is correspondingly successively greater.

A plurality of switch members in the form of brushes |24, |25, |26 and |21, which are connected in short-circuited relation by a strap or wire |29 and mounted suitably in insulated relation on the fly-Wheel 58, as by a bracket |28 attached to the one side of the fly-wheel near the outer rim thereof, are provided for cooperating with the switch members or contact segments I I5 to I2I. The brushes |24 to |21 are arranged in a row parallel to the longitudinal axis of the hub 43 and, in the normal positionk of the fly-wheel 58 with respect to the wheel 40, are so positioned as to be in the neutral plane bisecting the arcuate contact segment I I5.

The brush |24 normally engages the segment I|5 at the mid-point thereof and continuously engages the contact segment I|5 as the fly-wheel 58 shifts in either direction relative to the wheel 40. The brush |25 is in alignment with the contact segments II6 and II1, the brush |26 is in alignment with the contact segments I I8 and I I9, and the brush |21 is in alignment with the contact segments |20 and I2I. The brushes |25, |26 and |21 are normally out of contact with the segments and are positioned mid-way between the inner ends of the segments in alignment therewith.

Contact segments II5, IIE, II1, IIB, II9, |20, and |2I are connected'to the collector rings 88, 81, 86, 85, 84, 83, and 82, respectively, by wires |35, |36, |31, |38, |39, |40, and I4I, respectively, as shown in Fig. 4. The wires to |4| extend from the collector rings 82 to 88 to the contact segments II5 to I2I through a suitable longitudinal passage in the hub 43 and a radial passage in the web of the wheel 40, as shown in Fig. 2.

As will be explained hereinafter in further detail, the wire |08, which is connected to the brush 98 contacting the collector ring 88, is connected to one terminal of a source of current, such as the battery 22, by pneumatic switch device 21 upon an application of the brakes. Accordingly, the arcuate contact segment I I5 on the wheel 40, which segment is constantly connected to the collector ring 88, is also connected to the same terminal of the battery. In view of the fact that the brush |24 constantly engages the contact segment I I5 and in view of the fact that the brushes |24 to |21 are connected in short-circuited relation by the wire |29, it will be apparent that all of the brushes |24 to |21 are thereby also connected to the same terminal of the battery.

It will also be apparent that when the brushes |24 to |21 are shifted out of the neutral position thereof in either of the two opposite directions, the brushes |25, I 26 and |21 successively engage the associated contact segments II6, II8 and |20 or |I1, IIS and I2I, respectively, to close certain circuits which will be hereinafter described and which include battery 22.

For purposes of simplification, the collector rings 82 to 88 and the associated brushes 92 to 98 of the adhesion adapter devices I8 and Ia have been omitted from Fig. l, and instead of the wires |52 to |08 being connected directly to the brushes 92 to 98, respectively, they have been indicated as connected directly to the arcuate contact segments I2I, |20, II9, IIB, |I1, ||6, ||5,respectively. Likewise, contact segments IISa to |2Ia of the adhesion adapter device I8a, whichsegments correspond to the contact segments |I5 to I2I, respectively, of the adhesion adapter device I8, are indicated ashaving circuit connections directly thereto instead of through collector rings.

The adhesion adapter device |8a is connected in parallel relation to the adhesion adapter device I8, contact segment II5a being connected to the wire |08 by a branch wire |0801., the arcuate contact segments II1a, ||9a, and |2Ia being connected by branch wires I06a, |04a, and |02a, respectively, to the wires |06, |04, and |02, respectively, and the contact segments |I6a, ||8a, and |200. being connected by branch wires |010., |05a, and I03a, respectively, to the Wires |01, |05, and |03, respectively.

The coil spring 60 which resists relative movement between the fly-Wheel 53 and the wheel 40 is so designed and so adjusted in tension and the arcuate contact segments ||6 to |2| are so disposed and arranged that contact between the brush 25 and the inner end of the segments ||6 or I I1 occurs only when the rate of retardation of the car wheels which are fixed to the axle 36 associated with the adhesion adapter device I8 attains the rate of, for example, 5.5 miles per hour per second. The arrangement of the segments H8 and I I9 is such that the brush I 26 does not engage the inner ends thereof until the rate of retardation, produced on the car wheels of the axle 36 associated with the adhesion adapter device I8, attains the rate of, for example, 6.6V miles per hour per second.

The arrangement of the segments |20 and |2| is such that the brush |21 does not engage the inner end of the segments unless the rate of retardation produced on the car wheels of the axle associated with the adhesion adapter device I6 attains a rate in excess of, for example, '1.7 miles per hour per second, such as would result if the 7 car wheels began to slip, that is decrease in speed from the speed of rotation corresponding to the speed of travel of the car or train, toward zero speed corresponding to the locked condition of the car wheels.

If the wheel 40 accelerates with respect to the fly-wheel 58, the engagement of the brushes |25, |26 and |21 with the segments ||1, ||9 and IZI or with the segments 6, I I8 and |26 will occur at rates of acceleration corresponding to the rates of retardation above described.

The rates of acceleration or retardation of the car wheels at which the initial contact of the brushes |25, |26 and |21 with the segments Ill, IIS and |2I, or IIS, |I8 and |20, is eiected, may be varied by adjusting the tension of the spring 66 or by adjusting the position of the segments relative to the brushes |24 to |21. The degree of tensioning of spring' 60 and the required adjustment of the segments I6 to 2| to secure Contact of the brushes and segments at particular rates of acceleration or deceleration may be determined in any suitable manner, as by comparison with an electric motor of known acceleration characteristics.

It will thus be seen that, depending upon the direction of travel of the car or train at the time an application of the brakes is initiated, and depending upon whether the car wheels are being retarded or accelerated, the contact segments |51, ||9 and I2I, or I|6, ||8 and |20, may act as retardation contact segments or acceleration contact segments.

In order, therefore, to determine automatically whether the engagement of the brushes |25, |26 and |21 with the segments |6 to |2| associated therewith is due to retardation of the car wheels or to acceleration of the car wheels, the relays I9 and ISa are provided, these relays being thus aptly termed direction-determining relays. The manner in which the relays |9 and |'9a function will be described hereinafter.

(b) Control valve mechanism 16 The control valve mechanism I6, as shown in Fig. 5, comprises a suitable sectionalized casing |40 whereby the parts of the valve mechanism may be readily assembled and disassembled. For the sake of simplicity, however, the casing-|40 is illustrated without regard to sectionalization or construction whereby the parts may be assembled and disassembled.

Suitably assembled and arranged in the casing |46 are an application valve device 4|, a cut-olf valve device |42, a slow release valve device |43 and a fast release valve device |44, the valve devices |4| to |44 being controlled, respectively, by magnet valve devices |45, |46, |41 and |48. Also embodied in the casing |40 is a fluid pressure differential responsive interlock switch device |49.

The application valve device |4| comprises a Valve piston |I, slidably operative in a bore |52 and having, at one side thereof, a chamber |53 containing a coil spring |54 which is interposed between the valve piston and the casing for yieldingly urging the valve piston into seated relation on an annular rib seat |55. At the outer seated area of the valve piston I5I is an annular chamber |56 which is connected by a branch passage |51 to a supply passage |58 in the casing |40. The passage |58 is supplied with fluid under pressure from a suitable source, which in the embodiment shown in Fig. 1 is the straight-air pipe I3, through a branch pipe |59. Formed on the valve piston |5| is an annular rib |56 which seats on an annular gasket |56a, whenever the piston is shifted away from the seat |55, to prevent leakage of fluid under pressure past the valve piston.

Opening at the inner seated area of the valve piston |5| is a passage or chamber |6|,which contains a choke fitting |60 having a restricted port |6011 therein and which is connected by a passage |62 to a passage |63 leading to and opening into a chamber |64 to which the brake cylinder I2 may be connected, as by a branch pipe |65.

The application magnet valve device |45 comprises an electro-magnet |61 effective, when energized, to actuate a plunger or stem |68 to shift a double beat valve |69 from an upper associated valve seat to a lower associated valve seat, against the force of a biasing spring 1|. The double beat valve |69 is contained in a chamber |12 which is constantly connected to the chamber 53 at one side of the valve piston|5| by a passage |13. When the double beat valve |69 is seated on its upper valve seat it establishes communication past its lower valve seat from the chamber |12 to a chamber |14, containing the biasing spring |1| and connected by a passage tothe annular chamber |56 at the outer seated area of the valve piston |5I. When the double beat valve |60 is in seated relation on its lower valve seat it cuts olf communication between the chambers |12 and |14 at the lower valve seat and opens communication from the chamber |12 past its upper valve seat to a chamber |16 which is constantly open to atmosphere through a port |11.

It will, accordingly, be seen that when the electromagnet |61 of the application magnet valve device |45 is deenergized, the double beat valve |69 is unseated from its lower valve seat by spring |1| and thus establishes communication from the annular chamber |56 to the chamber |53, thereby effecting equalization of fluid pressures therein and rendering the biasing spring |54 effective to maintain the valve piston |5| seated on the annular rib seat |55. It will also be seen that when the electromagnet |61 of the application magnet valve device |45 is energized, the double beat valve is unseated from its upper valve seat and thus establishes communication through which fluid under pressure is'vented from the chamber |53 at one side of the valve piston |5|. The higher pressure of fluid in the annular chamber |56 acting on the opposite side of the valve piston |5| thus becomes eiective to overcome the tension of the biasing spring |54 and shift the valve piston |5| away from the annular rib seat |55 to open communication between the annular chamber |56 and the chamber |6|.

'I'he cut-off valve device |42 comprises a valve piston |8| slidably operative in a. bore |82 and having at one side thereof a chamber |83 containing a coil spring |84, which is interposed between valve piston |3| and the casing for yieldinely urging the valve piston |8| into seated relation on an annular rib seat |85. At the outer seated area of the valve piston |8| is an annular chamber 86 into which the fluid pressure supply passage |58 opens. The inner seated area of the valve piston |8| is open to the chamber |64 which, as previously described, is connected to the brake cylinder l2 by the branch pipe |65,

The cut-ofi magnet valve device |46, which controls the operation of the cut-off valve device |42, comprises an electromagnet |81 which is effective when energized to actuate a plunger or stem |83, to shift a pair of oppositely seating valves |89 and |90 against the force of a biasing spring |9|. The valve |89 is contained in a chamber |93, which is constantly open to atmosphere through a port |94, and the valve |90 is contained in a chamber |95, which is constantly connected to the uid pressure supply passage |58 through a branch passage |96. The fluted stems of the valves |89 and |90 meet in end-toend contact within a chamber |91 located between the chambers |93 and |95, the chamber |91 being constantly connected to the chamber |83 at one side of the valve piston |8| by a branch passage |98.

When the electromagnet |81 of the cut-01T magnet valve device |46 is deenergized, the biasing spring |9| is effective to seat the valve |90 and unseat the valve |89, thereby causing the seated valve |90 to cut oif communication from the chamber |95 to the chamber |91 and causing communication to be established past the unseated valve |89 from the chamber |91 and the connected chamber |83 to the atmospheric chamber |93. It will thus be apparent that, with the electromagnet |81 deenergized, the chamber |83 of the cut-off valve device |42 is vented and consequently uid under pressure supplie-d into the passage |58 will be effective to unseat the valve piston |8| and ilow through chamber |64 and pipe |65 to the brake cylinder |2.

The electromagnet |81, when. energized, causes the valves |89 and |90 to be shifted into seated and unseated positions respectively. The seated valve |89 thus cuts off communication from the chamber |91 and the connected chamber |83 to the atmospheric chamber |93, and the unseated valve |90 opens communication from the chamber |95 and the connected passage |58 to the chamber |91 and its connected chamber |83. If uid under pressure is now supplied from. passage |58 simultaneously to the chamber |83 and the annular chamber |86, the biasing spring |84 is effective to maintain the valve piston |8| seated on the annular rib seat |85 to prevent the supply of fluid under pressure from the passage |58 to the brake cylinder I2 past the valve piston |8|.

The slow release valve device |43 comprises a valve piston slidably operative in a bore 202 and having a chamber 203 at one side thereof containing a biasing spring 204 which is interposed between the valve piston and the casing for yieldingly urging the valve piston into seated relation on an annular rib seat 205. At the outer seated area of the valve piston 20| is an annular chamber 206 to which the passage |63 leading from the chamber |64 is connected.

At the inner seated area of the valve piston 20| is a chamber or passage 201, which is open to atmosphere through a choke fitting 208 having a restricted port 209 therein.

'I'he slow release magnet valve device |41 comprises an electromagnet 2|| which is effective, when energized, to actuate a plunger or stem 2|2 to shift a double beat valve 2| 3 against the resistance of a biasing spring 2|4 away from seated relation on an upper valve seat into seated relation on a lower valve seat. 'I'he double beat valve 2|3 is contained in a chamber 2| 5 which is constantly connected by a passage 2|5 to the chamber 293 at one side of the valve piston 20|. When the electromagnet 2|| of the slow release magnet valve device |41 is deenergized, the biasing spring 2|4 shifts the double beat valve 2|3 into seated relation on its upper valve seat and unseats it from its lower valve seat thereby closing communication past the upper valve seat from the chamber 2|5 to a chamber 2|1, which is constantly connected to atmosphere through a` port 2|8, and opening communication past its lower valve seat from the chamber 2| 5 to a chamber 2| 9 containing the biasing spring 2|4 and constantly connected to the annular chamber 206 by a passage 22|.

It will be apparent that when the electromagnet 2|| of the slow release magnet valve device |41 is deenergized, the fluid pressures in the chambers 206 and 203 at opposite sides of the valve piston 20| are equalized and thus the spring 204 is eiTective to maintain the valve piston 20| seated on the annular rib seat 205. When the electromagnet 2|| is energized, however, communication between the chambers 205 and 203 is closed and the chamber 203 is vented to atmosphere. Thus a higher fluid pressure exerted in the annular chamber 296 overcomes the tension on the spring 204 and unseats the valve piston 20| from the annular rib seat 205 to open communication from the brake cylinder to atmosphere by way of branch pipe |65, chamber |64, passage |63, passage 201 and restricted port 289 in the choke fitting 20B.

The cross-sectional area of the restricted port 209 in the choke fitting 203 is such as to cause uid under pressure to be released from the brake cylinder at a certain rate which will hereinafter be termed a slow rate.

The fast release valve device |44 comprises a valve piston 23| slidably operative in a bore 232 and having a chamber 233 at one side thereof containing a biasing spring 234 which is interposed between the valve piston 23| and the casing for yieldingly urging the valve piston 23| into seated relation on an annular rib seat 235. At the outer seated area of the valve piston 23! is an annular chamber 236 which is constantly connected by a branch passage 231 to the passage |62 that is constantly connected to the brake cylinder I2 through passage |93. chamber |64 and pipe |65. At the inner seated area of the valve piston 23| is a chamber or passage 238 which is open to atmosphere through a choke tting 239 having a restricted port 24| therein. The choke tting 239 is similar in appearance to the choke fitting 208 but the restricted port 24| has a larger cross-sectional area than the restricted port 209 for a reason which will be hereinafter made apparent.

The fast release magnet valve device |48 comprises an electromagnet 243 which is effective, when energized, to actuate a plunger or stem 264 toI shift a double beat valve 265 against the resistance oi a biasing spring 246 from seated Vposition on its upper valve seat to seated position on its lower valve seat. The double beat valve 265 is contained in a chamber 267 which is ccn-` stantly connected by a passage 248 to chamber 233 at the one side of the valve piston 23|.

When the electromagnet 263 is deenergized, the spring 246 urges the double beat valve into seated relation on its upper valve seat and unseats it from its lower valve seat, communicationV thus being cut oli at the upper valve seat from the chamber 267 to a chamber 249, which is constantly open to atmosphere through a port 25|, and communication being established past the lower valve seat from the kchamber 247 to a chamber 253 containing the spring 246 and constantly connected by a passage 254 to the annular chamber 236.

Thus, with the electromagnet 243 deenergized, the fluid pressures in thefannular chamber 236 and in the chamber 233 at opposite sides of the valve piston 23| are equalized and the spring 236 is effective to maintain the valve piston 23| seated on the annular rib seat 235. tromagnet 253 is energized, however, the connection between the chambers 236 and 233 is closed and the chamber 233 is vented toatmosphere through the port 25|. Accordingly, if the iuid pressure in the chamber 236 is higher than the pressure in the chamber 233 to a sufcient degree to overcome thetension of the spring 234, the valve piston 23| is unseated from the annular rib seatV 235 and fluid under pressure is accordingly released to atmosphere from the annular chamber 235 and the brake cylinder i2 connected thereto, through the restricted port 25H in the choke tting 239.

The purpose of the increased cross-sectional area of the restricted port 26|, as compared to the cross-sectional area of the restricted port 269 in the choke fitting 268 will now be apparent for obviously the restricted passage 26| enables a faster release'of iiuid under pressure and consequently a faster reduction in the pressure in the brake cylinder l2 than does the restricted port 262.

The fluid pressure interlock switch device |49 comprises a movable abutment, such as a diaphragm 256 suitably mounted in the casing |60 and carrying on one face thereof a follower 26| having in insulated relation thereon a contact bridging member 262, which is adapted to engage-and connect in circuit-closing relation a pair of' spaced insulated contact iingers 265 and 266 that are mounted on the casing within a chamber 265 at one side of theY diaphragm 259. A coil spring 25E) contained in chamber 265 and interposed Ybetween the follower on the dia phragm and the casing normally yieldingly urges the diaphragm downwardly so that the contact member 262 disengages the contact fingers 263 and 261i.

' The chamber 265 is constantly connected'by a branch passage 256 to the passage |62 which', as previously described, is constantly in corn munication with the brake cylinder l2. At the Vopposite side of the diaphragm 256 is a chamber 268 which is constantly connected to the supply passage |58 by a branch passage 269.

The contact of the contact bridging member 262 with the contact fingers 263 Yand 264 and the When the` elec- Y disengagement of the contact member 262 from the contact fingers 263 and 266 is controlled by the differential fluid pressure in the chambers 265 and 268 at opposite sides of the diaphragm 259. The tension of the coil spring 265 is such that when the pressure in the chamber 268 eX- ceeds the pressure in the chamber 265 by a small amount such as two or three pounds per square inch, the diaphragm is iieXed upwardly against the yielding resistance of the spring 266 into contact with the contact fingers 263 and 266. Conversely, if the pressure in the chamber 265 is substantially equal to or exceeds the pressure in therchamber 268, the spring 266 is eiective to shift the diaphragm 256 downwardly and thus cause the contact member 262 to disengage the contact ngers 263 and 264.

The circuits controlled by and the function oi' the interlock switch S49 will be made apparent hereinafter.

A one-way or check valve, shown as a ball check valve 27|, is provided in a passage 272 connecting the passages 258 and |62, the check valve 27| being eiective to prevent flow of fluid under pressure through the passage 272 from the supply passage |58 to the brake cylinder passage |62 but adapted to unseat and permit reverse iiow from the passage |62 to the passage |58 for a purpose hereinafter made apparent.

" (c) Additional equipment Energization and deenergization of the application magnet valve devicerl45, the cut-off magnet valve device |135, the slow release magnet valve device |137 and the fast release magnet valve device |68 of the control valve mechanism i6 is controlled by operation of the adhesion adapter devices |8 and iBa through the medium of electrical circuits which are conditioned, depending upon the caror train traveling in a forward or a backward direction at the time the application of the brakes is initiated, by the direction-determining relays i9 and |6a. The relays |9 and lea are shown in diagrammatic form and it will be understood that any suitable type of relay may be provided. It will also be understood that instead of a single relay such as the relay I9 or the relay iSd, a plurality of simultaneouusly energized and deenergized relays may be provided, the sum total of the contacts or switch members of all the relays corresponding to the total number of Contact or switch mem-- bers indicated by the relays I9 and |912.

As illustrated, the relay i9 comprises an electromagnet 275 having an associated magnetic core, not shown, and adapted when energized to actuate a plurality of contact members 276, 277, 273, 279 and 28| into circuit-closing contact with respectively associated pairs of spaced insulated contact fingers 282, 283, 285, 235 and 286, respectively. Relay |23 also comprises a pair of movable contact members 228 and 289, which are normally in circuit-closing contact with associated pairs of insulated contact fingers 29| and 252 when the electromagnet 275 is deenergized, and which are shifted out of engagement with the associated contact iingers upon the energization of the electromagnet 275.

The relay |911 being identical in construction tothe relay i9 will not be described in detail except to point out that corresponding parts in the two relays will be design-ated by the same reference numeral as in the description of the relay I9 except for the addition of the suffix a.

The method of controlling the relays I9 and I 9a and the function thereof will be made apparent hereinafter.

The pneumatic switch device 21 may be of any suitable construction such that, upon the supply of fluid under pressure thereto, it is actuated to circuit-closing position and upon the release of fluid under pressure therefrom it is actuated to circuit-opening position. As illustrated, the switch device 21 may comprise a suitable casing 30| containing a piston 302 having a stem 303 which carries in insulated relation thereon a contact member 304 adapted to engage a pair of insulated cont-act fingers 305 in circuit-closing relation, when fluid under pressure is supplied to a chamber 306 at one side of the piston. The pneumatic switch device 21 may be arranged in any suitable manner for operation to circuitclosing position' whenever fluid under pressure is supplied to the brake cylinder |2, as by a branch pipe 301 which connects the chamber 306 to the pipe |65, leading to the brake cylinder I2.

A spring 308 contained in a chamber 309 at the side of the piston 302 opposite to the chamber 306 and interposed between the face of the piston and the casing 30|, yieldingly resists shifting of the piston by the pressure of the fluid supplied to the chamber 306, and is effective whenever the pressure in the chamber 306 is reduced be- .low a relatively low pressure, such as two or three pounds per square inch, to shift the piston in a left-hand direction into contact with a stop lug 3|0 formed on or secured to the casing 30|, in which position of the piston, the contact member 304 is disengaged from contact fingers 305.

The wheel-slip control relay 29 and the retardation control relay 3| may be of any suitable construction. The relay 29 is illustrated diagrammatically as comprising an electromagnet 3|5 having associated therewith in the usual manner a magnetic core, not shown, and effective when energized to actuate a pair of movable contact members 3|6 and 3|0 into circuit-closing engagement with respectively associated pairs of insul-ated contact fingers 3|1 and 3|9, and at the same time to effect disengagement of a pair of movable contact members 322 and 324 from respectively associated pairs of insulated contact fingers 323 and 325. When the electromagnet 3|5 is deenergized, the contact members 3|6 and 3|8 are actuated out of engagement with their associated contact fingers and the contact members 322 and 324 are actuated into circuitclosing Contact with their associated pairs of contact ngers, either by gravity or by other suitable biasing means, not shown.

The relay 3| is illustrated diagrammatically as comprising an electromagnet 328 having associated therewith a magnetic core in the usual manner and effective, when energized, to shift a movable contact member 329 into circuitclosing contact with a pair'of insulated contact lingers 33|. When the electromagnet 328 is deenergize-d, the contact member 329 is shifted out of engagement with the contact fingers 33| either by gravity or by some suitable biasing means, not shown.

It is believed unnecessary to describe the various electrical circuits and circuit connections at this time for the reason that they will be described in connection with an assumed operation of the equipment.

OPERATION Application of the brakes, including automatic regulation of rate of retardation Assuming that the car or train is traveling in a forward direction, that the coefficient of adhesion between the car wheels and the track rails is in excess of twenty-five per cent, that the main reservoir is charged to full pressure in any suitable manner as from a fluid compressor, not shown, that the operating handle of the self-lapping brake valve device |4 is in release position, and that the equipment is otherwise conditioned as shown in Fig. 1, the operator may effect either a service or an emergency application of the brakes by shifting the operating handle |5 to service or emergency positions respectively. Assuming that the operator shifts the handle |5 to a service application position in the application zone, fluid under pressure is supplied from the main reservoir under the control of the self-lapping valve device |4 to the straight-air pipe |3 and thence to the brake cylinder I2 by way of the branch pipe |59, supply passage |58 of the control valve mechanism I6, annular chamber |86, past the valve piston 8| which is shifted downwardly by the pressure of the fluid in the chamber |86, chamber |64 and pipe |65. The pressure developed in the brake cylinder I2 corresponds to the degree to which the operating handle l5 is shifted out of release position.

With the electromagnet |61 of the application magnet valve device |45 deenergized as shown, the pressure equalizing communication between the chamber |56 and the chamber |53 at opposite sides of the valve piston |5| of the application valve device |4| is open and consequently fluid pressure is supplied to both chambers |56 and |53 from the supply passage |58 so that the spring |54 maintains the valve piston |5| seated.

In a similar manner, since the electromagnet 2|| of the slow release magnet valve device |41 is deenergized, the communication between the annular chamber 206 at one side of the slow release valve device |43 is connected to the chamber 203 at the opposite side of the valve piston and consequently fluid under pressure supplied to the chamber 206 from the chamber .|64 through the passage |63 is also supplied to the chamber 203. In view of the fact that the pressures are built up substantially simultaneously in the chamber 206 and 203 at opposite sides of the valve piston 20|, the spring 204 maintains the valve piston 20| seated.

Also in a similar manner, the valve piston 23| of the fast release valve device |44 is maintained in seated position due to the substantially simultaneous build-up of pressure in the chambers 236 and 233 at opposite sides of the valve piston, the electromagnet 243 of the fast release magnet valve device |48 being deenergized.

Fluid under pressure supplied to the chamber |64 and brake cylinder |2 also flows through the passages |63, |62 and 266 to the chamber 265 at the upper side of the diaphragm 259 of the interlock switch device |49. In view of the fact that the chamber 268 at the lower side of the diaphragm 259 is supplied with fluid under pressure directly from the passage |58 through the branch passage 269, there may be a slight differential in the pressure in the chamber 268 over that in the chamber 265 but insufficient to overcome the spring 260. In any case, even though the pressure in the chamber 268 is sufficiently higher,

` of the interlock switch |49 is Without effect at this Vtime as will subsequently appear.

Whenever the pressure built up in the brake cylinder I2 and-'accordingly in the chamber 306 of the pneumatic switch device 21 exceeds the relatively low value of two or three pounds per squareinch, the contactY member 352 is shifted into contact with the contact fingers 355 to con'- nect one terminal of the battery 22 to the contact segments I |5'and II'aof the adhesion adapter devices I8 and ISa, respectively, through a circuit which extends from the one terminal of the battery through a wire 34|, train wire 2li, branch wire 352, contact fingers 305 and contact member 304 of rpneumatic switch device 21, and wire |58.

Let it be assumed that the operator has operated the operating handle I5 of the self-lapping valvedeviceI to cause a pressure to be built up inthe brake cylinder I2 which applies the brake shoes to the car wheels of the Wheel truck, with which the adhesion adapter devices I8 and Ia are associated, the degree of the brakingV force being such as to cause shifting ci the y-wheel 58 relative to the wheel IB of theradapter device I8 to a sufficient degree that the brush |25 engages the inner end of the contact segment ||1.

The engagement of the brush with the contactV segment |I1, or the'engagement of the brush I25a with the contact segment I I1a, completes a circuit for energizing the electromagnet 215 of the direction-determining relay I9, this circuit extending from the terminal of the battery 22 (see Fig. l) to the contact segments I|5 and II50L as previously traced, and thence through the brush I24,.connector |29, brush |25, contact segment |I1,"vvire H15, a wire 344, contact fingers 292a and contact member 28911 of the direction-determining relay ISG, a wire 345, contact fingers'29l Yand contact member 288 of the direction-determining relay I9, Wires 346 and 351, electromagnet 215 and thence to the opposite terminal of the battery 22, as by connection to ground through a Wire 348, the terminal of the battery 22 opposite to that to whichthe Wire As previously stated, the Contact member 28| of the direction-'determining relay I9 is actuated into circuit-closing contact with the contact fingers 286 upon energization of the electromagnet 215 of the relay and, accordingly, a circuit is established for holding or maintaining the electromagnet 215 of the relay I9 energizedindependentlylof the connection through the adhesion adapter devices I8 and I8a, as long as the pneumaticr switchdevice 21 is in circuit-closing position, this circuit extending from the nongrounded terminal of the battery 22 through the pneumatic switchV device 21 to the wire |58, as previously traced, thence by a branch wire 35|, a Wire 352, contact fingers 286 and Contact mem-V ber 28| of relay I9, wire 341, electromagnet 215, wire 3138 and through groundto the opposite terminaljof .the Vbattery 22.

' When the Contact member 216 of the relay I9 engages the associated Contact :lingers 282 in circuit-closing relation due to the energization of the electromagnet 215 of the relay I9, a circuit is completed for energizing the electromagnet |81 of the cut-off magnet valve device |46, this circuit extending from the non-groundedV terminal of the battery 22 through the pneumatic switch device 21 and adhesion adapter devices I8 and Ia to the wire |86 as previously traced, thence by wire 324, contact ngers 282 and contact member 215 of relay I9, wires 354 and 355, electromagnet |81, a Wire S55 to ground and thus to the grounded terminal of the battery 22.

Upon the energization of the electromagnet |81 of the cut-ofi magnet valve device |45, the venting communication for the chamber |83 at the lower side of the valve piston |8I of the cutoff valve device |42 is closed and fluid underV pressure is supplied to the chamber |83 from the passage I58 in the manner previously described. Thereupon, the valve piston I 8| of the cut-off magnet valve device |42 is shifted into seated relation on the annular rib seat |85 to out off the further supply of fluid under pressure from the passage I58 to the brake cylinder I2.

In a similar manner the cut-off valve device |52 of other control valve mechanisms I6 associated with the brake cylinders on other wheel trucks throughout the length of the train are also operated to cut off the further supply of uid under pressure to the associated brake cylinders. As previously explained, the shifting of the brushes I2!! to |21 on the fly-wheel 58 of the ad- Y hesion adapter device I8 out of the normal posiltion thereof a suiiicient degree to cause contact of the brush |25 with the contact segment H1 occurs only when the braking force applying the brake shoes to the car Wheels is such as to- Droduce a rate of retardation on the car wheels of at least 5.5 miles per hour per second. As previously pointed out also, heretofore known brake control equipment, of either the speed-governor or the inertia-governor type, is ineffective to regulate to such a high rate of retardation.

. As is well known, the coemcient of friction between the brake shoes and the car wheels increases as the speed of the car or train decreases and, consequently, as the speed of the car or train reduces, the maintenance of the braking force corresponding to the attained brake cylinder pressure causes an increase in the rate of retardation on the car Wheels, since the force of retardation acting on the car wheels increases in proportion to the product of the braking force and the co'- eflicient of friction between the brake shoes and the car wh-eels. With the increase in the rate of retardation of the car wheels thus produced, the ily-wheel 58 of the adhesion adapter device I8 and in a similar manner, the fly-wheel 58a of the adhesion adapter device I 8a are shifted or displaced to a further degree out of the normal or neutral position thereof to a sufiicient degree to cause the brushes |26 and |25a thereof to engage the inner end of the contact segments H9 and I lila, respectively.

Such contact of the brush I 28 with the contact segment I I9, or the contact of the brush I2Sa with the contact segment IIBa, completes a circuit for energizing the -electrornagnet 328 of the retardation control relay 3 I, this circuit extending from Ythe non-grounded terminal of the battery 22 through the pneumatic switch device 21 to the brushes |24, |25 and |26 as previously described, thence through contact segment |I9, wire |04,

Contact fingers 283 and contact member 211 of the relay I9, a wire 358, train wire 25, a branch Wire 359, contact lingers 323 and contact member 322 of the control relay 29, a wire 36|, electromagnet 328 of the relay 3| and to the grounded terminal of the battery 22, as by a wire 362 connected to ground.

Since the retardation control relays 3| for control valve mechanisms I6 (not shown) associated with other Wheel trucks, are similarly connected to the train wire 25 it follows that they are also energized simultaneously with the energization of the relay 3| independently of whether or not the brush |26 or I26a of the adhesion adapter devices associated with such wheel trucks contact the segments |I9 and Il9a, respectively. It follows, therefore, that the control relays 3| for all the control valve mechanisms I6 are substantially simultaneously energized upon the rst engagement of a brush |26 of any of the adhesion adapter devices with its associated contact segment |I9.

The actuation of the contact member 329 of the relay 3| into circuit-closing relation with the contact finger 33|, due to the energization of the electromagnet 328, completes a circuit for energizing the electromagnet 2 I I of the slow release magnet valve device |41, this circuit extending from the non-grounded terminal of the battery 22 through the train wire 24, pneumatic switch device 21, adhesion adapter devices I8 and lilay in parallel, to the wire |06 as previously traced, thence' through the wire 344, contact fingers 232 and contact member 216 with the relay I9, wire 354, a branch wire 364, contact ngers 33| and contact member 329 of relay 3|, a wire 365, electromagnet 2II of the slow release magnet valve device |41, and to the grounded terminal of the battery 22 as by connection to ground through a Wire 366.

As previously pointed out, the engagement of the brush |26 with the contact segment II9, or of the brush I26a with the contact segment I I9a, occurs only when the retardation force on the car wheels is such as to cause the rate of retardation on the car wheels to increase to, for example, 6,6 miles per hour per second.

Since the brushes, corresponding to the brushes |24 to |21 of the adhesion adapter device I8, of the adhesion adapter devices associated with all the wheel trucks have been shifted sufliciently that the brush corresponding to the brush |25 engages the segment corresponding to contact segment II1, it follows that the energization of the ccntrol relay 3| for each of the wheel trucks completes circuits corresponding to that just traced, for energizing the electromagnet of the slow release magnet valve device on the control valve mechanism for other wheel trucks corresponding to the control valve mechanism I6 and, accordingly, that the result produced is the same for all control valve mechanisms I6.

As previously indicated, the energization of the electromagnet 2II of the slow release magnet valve device |41 causes the pressure in the chamber 203 at the lower side of the valve piston 20| of the slow release valve device |43 to be vented to atmosphere and, consequently, the higher brake cylinder pressure existing in the annular chamber 206 at the opposite side of the valve piston 20| overcomes the spring 204 and shifts the valve piston 20| away from the annular rib seat 205, to open the communication for venting fluid under pressure from the brake cylinder to atmosphere through the pipe I 65, chamber |64, passage |63,

annular chamber 206 past the unseated valve piston 20|, passage 201, and restricted port 209 in the choke fitting 208.

Reduction in the pressure in the brake cylinder I2, and in all of the brake cylinders associated with other wheel trucks is thus effected at a rate determined by the size of the restricted port 209. The rate of reduction in brake cylinder pressure through the port 209 is such that the respective ily-Wheels 58 of the adhesion adapter devices I8 and I8a recede gradually toward their normal or neutral positions sufficiently that the brush |26 disengages contact segment I I9 and the brush |26a disengages the contact segment II9a. The rate of reduction in brake cylinder pressure through the port 209 is not, however, rapid enough to produce recession of the fly-wheel 58 toward its normal or neutral position to a suflicient degree to effect the disengagement of the brush |25 from the contact segment I1 or the disengagement of the brush |2511l from the contact segment I1a.

It will be apparent, therefore, that as a result of the iinal disengagement of all the brushes |26 and |26a of all the adhesion adapter devices for all wheel trucks from the contact segments II9 and II9a, respectively, the circuit for energizing the relay 3| for each wheel truck is interrupted and, consequently, the circuit established by each of the relays 3| for energizing a corresponding slow release magnet valve device |41 is interrupted. As a result, the valve piston 20| of the slow release valve device I 43 is again seated on the annular rib seat 205 to prevent further reduction in brake cylinder pressure through the port 209. In View of the fact that the brushes |25 and I25a remain in engagement with the contact segments II1 and II1a, respectively, the circuit previously traced for energizing the cut-off magnet valve device |46 is not interrupted and, consequently, the valve piston I8I of the cut-off valve device |42 remains seated to prevent any increase or build-up in brake cylinder pressure by ow of fluid under pressure there-past from the passage |58 in which, it will be understood, the original pressure established by operation of the operating handle I5 of the self-lapping valve device I4 remains.

As the speed of the car or train reduces further, the increase in the coefficient of friction between the brake shoes and car wheels may again produce such an increase in the rate of retardation on the car wheels as to effect reengagement of the brushes |26 and I26a with the contact segments II9 and ||9a of the adhesion adapter devices I8 and I8a, respectively. In such case, the operation just described is repeated and the pressure in the brake cylinder I2 and in the brake cylinders associated with other wheel trucks further reduces. It will thus be apparent that the adhesion adapter devices I8 and IBa :function automatically to regulate the rate of retardation produc-ed on the car or train to a substantially constant rat-e, in a manner similar to inertia-governor devices of brake control equipments heretofore known except that the rate of retardation is higher than the rate of retardation effected by heretofore known devices and equipments.

In the foregoing operation, it was assumed that the coefficient of adhesion between the car Wheels and the track rails was twenty-five per cent or over and that the braking ratio, that is, the ratio of the total braking force acting on the wheels of a wheel-truck with respect to the total load or force pressing the Wheels of the wheeltruck to the rails is such that Vthe braking forces which produce a rate of retardation on the car wheels of 6.6 miles per hour per second are insumcient to overcome theforce of adhesion between the car wheels and the track rails. If, therefore, the actual coelicient of adhesion between the car wheels and the track rails is in excess of twenty-five per cent practically seventyve per cent of the time the train is in service,

it will be seen that notwithstanding the retardation of the car wheels at a rate up to 6.6 miles per hour per second, no sliding of the car wheels will occur the majority of the time. In view of the fact that the brake control equipment comprising my invention regulates the rate of retardation of the train automatically to a substantially constant rate higher than that to which heretofore known devices and equipments have attained, it will be seen .that a car or train provided with my brake control equipment may be brought to a stop from a given high speed `in a much shorter distance than has heretofore been possible.

When the car or train is brought to a complete stop, the brushes I2@ to |27 and i265@ to I2'Ia of the adhesion adapter devices I 8 and I8a, respectively, return to the normal or the neutral position thereof. Upon the disengagement of the brushes I25 and I25a from the contact segments IIT and IIla respectively, the circuit for energizing the electromagnet ISI of thercut 01T magnet valve device I 45 is interrupted and the electromagnet consequently deenergized. As a result, the pressure established in the straightair pipe I5, in the supply passage |58, and in the annular chamber I86 ofthe control valve mechanism I6, as well as the brake cylinder pressure in the chamber |64 unseats the valve piston I 8| ofthe cut-olf valve device |42. Fluid under pressure is accordingly again supplied from the straight-air pipe I 3 to the brake cylinder to build up the pressure in the brake cylinder substantially to the pressure established originally in the straight-air pipe. Thus, although the brake cylinder pressure is reduced, as previously described, by operation of the control valve mechanism to maintain a substantially constant rate of retardation of the vehicle, adequate braking force is automatically restored when the train is completely stopped in orderto insure against undesired creepage or movement of the train.

AThis feature of the invention whereby full braking force is automatically restored is particularly advantageous in cases where the train stops on a grade.

It will be apparent that, with the brushes of the adhesion adapter devices in the neutral position thereof, the brake cylinder pressure maybe increased as desired up to the maximum possible degree by operation of the self-lapping valve device I, because the cut-olf valve device |42 will admit uid under pressure to the brake cylinder to substantially whatever degree is established in the straight-air pipe I3.

Release of the brakes After the car or train has been brought to a complete stop, and it is desired to again start the car or train under power, the brakes may be released by returning the operating handle I5 of the self-lapping valve device I4 to release position wherein the self-lapping valve device I4 functions in well'known manner to vent iuid under pressure from the straight-air pipe and accordingly reduce the pressure therein to atmospheric pressure. As will be seen .in Fig. 5, the reduction of pressure in the straight-air pipe I3 produces a corresponding reduction of the pressure in the supply passage |58 of the control valve mechanism I6 and when the pressure in the passage |58 reduces below the pressure in the bra-ke cylinder I2 and consequently in the passage IGZ, the higher pressure unseats the check valve 27| and fluid under pressure is thus released from the brake cylinder I2 by flow from the passage |62 through the passage 2'52, past the check valve 21|, and through passage |58, pipe |59, straight-air pipe I3 and to atmosphere under the control of the self-lapping valve device I 4. Thus, the pressure in the brake cylinder I2 may be reduced to completely release the brakes, independently of either the slow release valve device |43 or the fast release valve device IM by merely returning the operating handle of the self-lapping valve device I4 to release position.

When the car or train is stopped and the brushes of the adhesion adapter devices I8 and I8@ are in neutral position, fluid under pressure may also be released from the brake cylinder I2 past the cut-off valve device I 42 as well as past the check valve 2'II, because the pressure acting in chamber |64 on the innerl seated area of the valve piston ISI and in chamber |36 at the outer seated area of the val-ve piston is effective to overcome the spring |84 and unseat the valve piston I8I to permit release ow of fluid under pressure therepast in by-passing relation to the check valve 21 I.

It Awill be apparent that a graduated release of the brakes may be effected at any time by operating the self-lapping valve device Ill to reduce the pressure in the straight-air pipe I3 and thus in the brake cylinder I2 in a series of successive steps.

Anti-wheeZ-slz'dzng operation In the foregoing hypothetical operation, it was assumed that the coefficient of adhesion between the ear wheels and the track rails was high enough so that the braking forces effective were insucient to cause wheel slipping or wheelslid-V ing. Let it now be assumed that, due to moisture, frost or other agents on the rails or wheels, the coeflicientV of adhesion between the car wheels and the track rails is reduced to, for example, fifteen per cent. Thus, upon an application of the brakes initiated in the manner previously described, the braking force applying the brake shoes to the car wheels will be such as to cause the car wheels on the axle 3B associated with the adhesion adapter device I8 to begin to slip, that is, reduce from the speed of rotation corresponding to the speed of travel of the train toward zero speed corresponding to the locked condition of the car wheels. In a very short interval of time following the instant that the car wheels begin to slip, relative movement between the wheel 4Il and iiy-wheel 58 will take place and cause shifting of the brush |25 on the fly-wheel 58 into Contact with the contact segment I I`| and, consequently, in the manner previously described the electro-magnet |81 of the cut-off magnet valve device |46 is energized and prevents the further supply of fluid under pressure to the brake cylinder. It has been found that when the braking force applying the brake shoes to the car wheels exceeds, by only aY slight amount, that braking force which will initiate slipping of the wheels, the slipping time, that isY the interval of time required for the oar wheels to decelerate from a speed corresponding to the speed of travel of the train to zero speed corresponding to the locked condition of the Wheel is appreciably longer than if the braking force were considerably in excess of the minimum amount which will initiate or produce slipping of the wheels. Consequently, by providing suitable relays I9 and |9a which respond quickly to the energization of the electromagnets thereof and thus cause an immediate cutting orf of the flow of iiuid under pressure to the brake cylinder, the slipping time for the car Wheels is lengthened as much as possible, thereby enabling the subsequent reduction in brake cylinder pressure, as effected in the manner to be presently described, to take place rapidly enough so as to prevent the car wheels from decelerating to zero speed and thus to a locked condition. Accordingly, in the operation of my invention a slipping time of from threequarters of a second to one second may be dependably realized Once the car wheels associated with the axle 36 of the adhesion adapter device I8 begin to slip, the rate o retardation in the rotative speed of the car wheel increases rapidly so that the flywheel 58 is rapidly shifted relative to the wheel 4I) to such a degree that the brush |21 engages the inner end of the contact segment I2I, the interval o time over which the increase in the rate of retardation in the rotative speed of the car wheels takes place being only a fraction of a second.

It is assumed for the moment that only the car wheels on the axle 36 associated with the adhesion adapter device I8 begin to slip but it will be understood that, in the event the car wheels on the axle associated with the adhesion adapter device I8a. also begin to slip, the brush |210. of the adhesion adapter device |811. will be rapidly shifted into contact with the contact segments |2|a as in the case of the adhesion adapter device I8. It will be understood that the brake cylinder I2 or a plurality of parallel connected brake cylinders acting in the place of the brake cylinder I2 are effective to apply the brakes only on the car wheels of the axles associated with the adhesion adapter devices I8 and |8a. It will thus be clearly seen that whether the adhesion adapter devices I8 and IBa are separately actuated, as just described, or whether both the adapter devices I8 and I8a are simultaneously actuated, the effect will be the same.

Upon the engagement of the brush |21 of the adhesion adapter device I8 with the segment I2 I, a circuit is completed for energizing the electromagnet 3|5 of the wheel-slip control relay 29 and also the electromagnet 243 of the fast release magnet valve device |48. This circuit extends from the nongrounded terminal of the battery 22 through the train wire 24 and pneumatic switch device 21 to the brushes |24 to |21, in the manner previously traced, and thence through the contact segment I2I, wire |02, a wire 315, contact lingers 284 and contact member 218 of the relay I9, and a wire 316 to the point 311 whence the circuit divides into two branches, the one branch extending by way of a wire 318, contact fingers 325 and contact member 324 of the control relay 29, wires 319 and 38|, electromagnet SI of the relay 29, wire 382 to ground and, through ground, back to the grounded terminal of the battery 22. The other branch of the circuit extends from the point 311 through the wire 318, electromagnet 243 of the fast release magnet valve device |48, wire 383 to ground and thence, through ground, to the grounded terminal of the battery 22.

The magnet valve device |48 responds very rapidly and causes venting of the chamber 233 at the lower side of the valve piston 23| of the fast release magnet valve device |44, and the higher brake cylinder pressure effective in the annular chamber 236 at the outer seated area of the valve piston 23| accordingly unseats the valve piston 23| against the force of the spring 234 and thus reduces brake cylinder pressure by iow past the Valve piston 23| through the passage 238 and port 24| in the choke iitting 239, which port is quite appreciably larger than the slow release port 209, as before described, and, therefore, permits a more rapid iow to the atmosphere.

At the same time, the energization of the electromagnet 3|5 of the control relay 29 causes engagement of the contact member 3|8 with the contact fingers 3|9. A holding circuit is thus established for maintaining the relay 29 energized independently of whether the brush |21 subsequently recedes out of contact with the segment I2I toward its normal or neutral position. This holding circuit extends from the battery 22 through the train wire 24, pneumatic switch device 21, brush |25 and contact segment II1 of the adhesion adapter device I8, in the manner previously described, and thence through the wire |06, wire 344, contact fingers 282 and contact member 216 of the relay I9, wires 354 and 355, contact fingers 3|9 and contact member 3| 8 of the relay 29, wire 38|, electromagnet 3|5 of the relay 29, wire 382 to ground, and thence to the grounded terminal or the battery 22 through ground.

At the same time, the Contact member 322 of the relay 29 disengages the contact iingers 323 to interrupt the previously traced circuit for energzing the electromagnet 328 of the relay 3|, which circuit was established in the` manner previously described, upon contact of the brush |26 with the contact segment ||9 of the adhesion adapter device I8. Consequently, although the circuit for energizing the slow release magnet valve device |41 may be momentarily completed by the momentary energization of the relay 3|, such energization is only momentary for the reason that the relay 29, when energized, immediately causes deenergization of the relay 3| and consequently the deenergization of the slow release magnet valve device |41.

In View of the fact that the chamber 265 at the upper side of the diaphragm 259 of the interlock switch device |49 is constantly connected to the brake cylinder passage |62, the reduction in brake cylinder pressure effected by the fast release valve device |44 effects a similar reduction in the pressure in the chamber 265. Consequently, when the pressure in the chamber 268 at the lower side of the diaphragm 259, which pressure corresponds to the pressure in the supply passage |58 and which is maintained, exceeds the pressure in the chamber 265 by a suiiieient amount to overcome the tension of the spring 260, the diaphragm 259 is flexed upwardly to eiect engagement of the contact member 262 with the contact ugers 263 and 264 and thereby establish an additional holding circuit for maintaining the electromagnet 3I5 of the relay 29 energized, notwithstanding that the brush |25 of the adhesion adapter device I8 may recede out of contact with the contact segment |I1 toward the normal neutral position thereof. This holding circuit extends from the non-grounded terminal Vof the battery 22 through Wire 34|, contact nger 263 of the interlock switch |49, contact member 262, Contact finger 264, a wire 385, Contact fingers 3|7 and contact member 3|6 of the relay 29, a Wire 386, wire 38|, electromagnet 3|5 of relay 29, Wire 382 to ground and thence to the grounded terminal of the battery 22 through ground. At the same time also, engagement of the contact member 262 of the interlock switch |49 with the contact fingers 263 and 264 completes a holding circuit for maintaining energized the electromagnet |87 of the cut-off magnet valve device |46, independently of the recession of the brush |25 out of contact with the contact segment ||7 of adhesion adapter device |8 toward its normal neutral position. This holding circuit extends from the battery 22 through the interlock switch |49 and contact fingers 3|7 and contact member 3|6 of the relay 29 to the wire 38|, in the manner previously traced, and thence by way of contact fingers 3|9 and contact member 3| 8 of the relay 29, Wire 355, electromagnet |87, Wire 356 to ground, and thence to the grounded terminal of the battery 22 through ground.

The size of the port 24| in the choke fitting 239 of the fast release magnet valve device |44 is such `that the pressure in the brake cylinder |2 is reduced rapidly enough, upon the unseating of the valve piston 23|, that in a fraction of the total slipping time, the brake cylinder pressure and accordingly the retardation force on the car wheels which began to slip is reduced suiciently that the rate of retardationV is reduced to zero after which the wheels accelerate rapidly back toward a rotation speed corresponding to the speed of the car or train.

The car wheels accelerate rotatively at a rate "which is much morerapid, than the rate of ro,-

tative retardation incident to slipping, in view of the relatively light Weight or mass of an individual car Wheel, or a wheel-and-axle unit relative to the total Weight of the car or train. In view of the rapid rate of vacceleration of the car wheels, the total period of time over which the acceleration occurs is less than the interval of time over which retardation occurred and during which the fast release valve device |44 was effective to release iiuid under pressure from the 'brake cylinder. It will be apparent that, when the rate of vretardation of the car wheels which began to slip is reduced sufficiently to cause the fly-wheel 58 to recede back toward its normal or neutral position and thereby eiect disengagement'` of the brush |27 from the contact member |2|, the circuit for energizing the electromagnet 243 ofthe fast release magnet valve device |48 is interrupted and, consequently, the fast release valve. device |44 is immediately and rapidly actuated to close oi communication through which fluid under pressure flows to atmosphere through the port 24| of the choke tting 239.

Since the car Wheels associated with the axle 36 of the adhesion adapter device |`8 accelerate at an exceedingly rapid rate, the ily-wheel 58 tends to lag behind the wheel 40 and, consequently, the brushes |24 to |27 are shifted in the righthand direction, as viewed in Fig. 1, `so as to effect engagement of the brushes |25, |26 land |27 with the contact segments '||6, ||8 land |20, respectively.V

The contact segment V| I6 is connected by the wire |67 and a 'wire 388 to one of the vcontact ngersv292 of the relay |'9 and one of the Contact members 282a of the relay 19a. VWith the relay |9 maintained energized, however, through the holding circuit previously traced, the contact member 289 thereof isdisengaged from the contact fingers 292. Also, since the relay lila, is deenergized, the contact member 276a is disengaged from the contact fingers 282a. Consequently, the contact segment H6 of the adhesion adapter device is electrically isolated and the engagement of the brush |25 therewith is without eiect.

The contact segment |8 of the adhesion adapter device 8 is connected by the wire |65 to one of the contact fingers 283a of the relay |9a, but with the relay |9a deenergized the contact member 277a is disengaged from the contact ngers 283a. Accordingly, the contact segment ||8 is also isolated electrically and the engagement of the brush |26 therewith is without eiect.

The engagement of the brush |27 with the contact segment |26, however, completes a circuit for energizing the electromagnet |67 of the application valve device |45, this circuit extending from the battery 22 to the brush |27 in the manner previously described, thence through Contact segment |28, wire |63, a wire 35|, contact fingers 285 and contact member 279 of the relay I9, a

' Wire 392, electromagnet |67 of the magnet Valve device |45, a wire 393 to ground, and thence to the grounded terminal of the battery 22 through ground.

Energization of the magnet valve device |45 thus causes the chamber |53 at the lower side of the valve piston of the application valve device |4| to be vented to atmosphere. Consequently, the valve piston |5| is unseated by the higher pressure in the annular chamber |56 as supplied from the supply passage |58. Fluid under pressure is accordingly supplied from the supply passage 58 to the brake cylinder l2 through the passage |57, annular chamber |56, past the unseated valve piston |5l, passage |6|, port |65a in choke tting |56, passage |52, |53, chamber |64, and'pipe |65. The port |68@ in the choke tting |68 is of any suitable size and may be of such size that fluid under pressure is supplied to the brake cylinder therethrough at substantially the same rate as it was vented from the brake cylinder through the port 24| of the choke fitting 23S.

As the rate of acceleration of the wheels which began to slip, decreases, that is, as the rotative speed of the Wheels approaches the speed coiresponding to the speed of travel of the car or train, the lagging effect of the fly-wheel 53 becomes less pronounced and consequently the brushes |24 to |27 recede back toward the normal or neutral position thereof so that disengagement ofthe brushes |27, |26 andr|25 from the contact segments |28, H8 and H5, respectively, is effected.

Disengagement of the brush |27 from the contact segment |2| interrupts the circuit for energizing the electromagnet |67 of the application magnet valve device |45. Consequently, equalization of the pressure in the chambers |55 and |53 at opposite sides of the valve piston |5| oi the application valve device |4| is restored and the application valve piston |5| is reseated to close off the further supply of fluid under pressure from the passage |58 therepast to the brake cylinder.

In View of the fact, however, that the time required for the wheels which began to slip to accelerate back to a 'speed of rotation corresponding to the speed of travel of the car or train is shorter than the time over Which fluid under pressure was released from the brake cylinder through port 24|, it will be seen that the degree to which the pressure of the brake cylinder is rebuilt by unseating of the valve piston II of the application valve device |4| will be lower than the pressure to which it was originally built up and which initiated the slipping of the Wheels.

As previously explained, the cut-off valve device |42 is operated Very rapidly to cut off the supply cf fluid under pressure to the brake cylinder following the engagement of the brush |25 with the contact segment II'I of the adhesion adapter device I8, and thus prevents the brake cylinder pressure from attaining a value much higher than the minimum pressure which will produce or cause slipping of the wheels. Therefore, since the pressure which is reestablished in the brake cylinder pressure by operation of the application valve device |4I will be appreciably less, it follows that the likelihood of the reestablished pressure causing the wheels to slip is unlikely.

It will be observed that the operation of the adhesion adapter devices I8 and IBa in preventing sliding of the car wheels on the axles with which they are associated is entirely local and without effect as respects the control of brake cylinder pressure to prevent sliding of the wheels on other wheel trucks. Therefore, on those wheel trucks where there is no tendency for the wheels to slip or slide, the adhesion adapter devices I8 and I8a function in the manner previously described to regulate the rate of retardation of the wheels for the individual trucks to the particular rate for which the adhesion adapters are designed.

The reason for and the function of the interlock switch |49 should now be apparent, for in the shifting of the brushes from the retardation contact segments I2I, ||9, and II'I on one side of the neutral position thereof to the acceleration contact segments |20, ||8 and IIB on the opposite side of the neutral position thereof, the brush |25 completely disengages the contact segment II"I and would thereby interrupt the circuit for energizing the electromagnet of the cut-off magnet valve device |46 unless the circuit were otherwise maintained. However, in order to limit the resupply or readmission of uid under pressure to the brake cylinder to the control of the application valve device I4I, it is necessary that the cut-off valve device |42 remain closed.

In view of the fact that the brake cylinder pressure and consequently the pressure in the chamber 265 at the upper side of the diaphragm 259 of the interlock switch |49 is not restored to the pressure in the straight-air pipe I3 and that in chamber 268 at the lower side of the diaphragm 259, the interlock switch contact 262 remains in engagement with the contact ngers 263 and 264 and, accordingly, maintains 'the holding circuit for both the relay 29 and the electromagnet of the cut-off magnet valve device Ii6, unless and until the self-lapping valve device I4 is operated to reduce the pressure in the passage |58 and in the chamber 268 substantially to the pressure in the chamber 265 of the interlock switch device |49.

Thus, notwithstanding that under wheel-slipping conditions the control of brake cylinder pressure is taken automatically out of the hands of the operator, the operator may retain a certain amount of control over the brake cylinder pressure by reason of his ability to reduce pressure in the straight-air pipe I3 by operation of the self-lapping brake valve device I4.

If, therefore, following the operation of the equipment in the manner just described to partially restore the pressure in the brake cylinder, the operator operates the self-lapping valve device I4 to reduce the pressure in the straight-air pipe supply passage |58 and chamber 268 at the lower side of the diaphragm 259 of the interlock switch device |49 to a pressure substantially equal to that restored in the brake cylinder and, accordingly, in the chamber 265 at the upper side of the diaphragm 259, the spring 269 becomes effective to shift the diaphragm 259 downwardly and thus causes separation of the contact member 262 from thecontact fingers 263 and 264. The holding circuit for maintaining energized the electromagnet of the cut-olf magnet valve device I46 and the electromagnet 3I5 of the relay 29 is accordingly interrupted and the magnet valve device and electromagnet deenergized. With the re-engagement of the contact member 322 of the relay 29 with the contact fingers 323, the electromagnet 328 of the relay 3| is reconnected to the train wire 25. Thereafter, the adhesion adapter devices I8 and |8a control the operation of the cut-off magnet valve device I 46 and the slow release magnet valve device I 41 in the manner previously described to regulate the rate of retardation for the car wheels associated therewith to a substantially constant rate.

It will be apparent that unless the operator does reduce the pressure in the straight-air pipe to cause opening of the interlock switch device |49, the adhesion adapter devices are ineffective after the wheel slipping condition is relieved, to control the slow release valve device |43 in the manner previously described, to release fluid under pressure from the brake cylinder, for the reason that the circuit for energizing the retardation relay 3| is held open by the wheel slip relay 29. However, in the event that the reduced brake cylinder pressure is suicient to again initiate slipping of the wheels at a lower speed, the adhesion adapters again function to prevent sliding of the wheels.

In the same manner as previously described for application of the brakes without wheel-slipping, the brushes |24 to |21 and I24a to I2'Ia of the adhesion adapter devices I8 and |8a, respectively, return to their normal or neutral positions upon the train being brought to a complete stop. Assuming that the operator has previously reduced the pressure in the straight-air pipe I3 sufficiently to cause opening of the interlock switch device |49, the cut-off magnet valve device |46 is accordingly deenergized and, consequently, the valve piston |8| of the cut-off valve device I 42 is unseated so that the pressure in the brake cylinder and in the straight-air pipe I8 becomes substantially equalized.

If the operator does not reduce the pressure in the straight-air pipe' following the occurrence of wheel-slipping, and the interlock switch device I 49 remains in closed position at the time that the train is brought to a complete stop, then the holding circuit for maintaining the electromagnet of the cut-oif magnet valve device |46 energized is maintained and, consequently, the valve piston |8I of the cut-off valve device |42 will not be unseated. Thus, the pressure in the brake cylinder associated with the control valve mechanism I 6 and adhesion adapter devices for the wheels which slipped is not restored automatically 

